OPPO has just released the HA-2 DAC and Headphone amplifier. It is sized to use with your smart phone’s digital output using a USB-micro-to-USB-micro cable. With a Sabre Mobile DAC and balanced operation, the HA-2 will decode up to 32/384 PCM and DSD256 music stored on your phone. You will need either an Android downloadable app (USB Audio Player Pro), or the same app from the iTunes store. The HA-2 plays high resolution music with proper transients that might otherwise be lost on the inexpensive DACs that are native to the smart phones.

The HA-1 has two digital inputs, one for iPhones (standard USB jack) and other smart phones (USB micro jack). A pair of strong rubber bands (included) holds the phone and the HA-2 together. The unit is about the same size as the smaller version of the iPhone 6.

The sound, using the HA-2, has more detail than the audio output of the phone, so it is a valuable addition to your phone , not only in looks (COOL FACTOR = 9.7 out of 10), but in delivering the transients that high resolution music has.

At $299, the HA-2 is a no-brainer, for updating your smart phone to play high res music.

The OPPO HA-2 DAC and Headphone Amplifier Review Highlights Summary

OPPO Quality

Improved detail compared to a smart phone’s native DAC

Plays up to 32/384 PCM and DSD256

Inexpensive

Very cool, and will get your friends’ attention immediately

Introduction to The OPPO HA-2 DAC and Headphone Amplifier Review

The brand name OPPO needs no introduction. Whenever they release a new product, audiophiles take notice.

The HA-2 is a DAC and Heaphone Amplifier, all contained in a chassis about the same size as the smaller iPhone 6. That is no coincidence. It is made to be used with the iPhone 6 and other smart phones of that size.

It has jacks on one end, as shown above, with a small sliding button on the left. The standard USB jack is for iPhones, and the USB micro jack on the far right is for Android and other smart phones.

One the other end are the volume control (far left), a jack for headphones, and a jack for line-out (about 1 volt RMS – the volume control does not affect this).

The HA-2, although only $299, contains the ESS Sabre32 Reference ES9018-K2M DAC chipset. This is the mobile version of the chip.

There are two digital inputs, one for iPhones/iPads, and the other for Android products. There is also a 1/8″ stereo analog input on the other end of the HA-2. This is for players that don’t have a USB digital output, so just the amplifier portion of the HA-2 is used. The two digital inputs and analog input are selected by a slider switch, that is labeled A, B, and C.

The edge has bass boost and high/low gain slider switches, as well as a button that, when pressed, lights up a series of LEDs that indicate the amount of battery power remaining.

Two large rubber bands come with the unit, so that you can wrap your iPhone and the HA-2 together. However, they do get in the way of using your phone, so you may want to use four regular rubber bands – two horizontally and two vertically – so that you can push them aside to touch the buttons on your phone. Here is a photo of the Samsung Note 2 on top of the HA-2.

The OPPO DAC and Headphone Amplifier In Use

I used a Samsung Note 2, which is larger than the HA-2. I bound them together with four rubber bands as described on the previous page. I loaded the phone with some high resolution (24/192) music, as well as test signals. I also used the line-out for connection to a Pass Labs Xs preamplifier, Pass Labs Xs 300 monoblocks, and Carver Mark IV ribbon speakers.

The sound was better than the sound coming directly from the phone’s analog output, but the main advantage is that the HA-2 has a much better battery, which will drive a planar magnetic headphone, such as the OPPO PM-1. This, to me, far outweighs the slight, but noticeable improvement in detail and sparkle, which I doubt would be discernible when using inexpensive earbuds (the earbuds that come with your smart phone).

The USB-micro-to-USB-micro cable is a bit short, and tends to come loose because it has to be twisted to go into the jack of the phone and the jack of the HA-2. However, a longer cord would get caught on something, so the short cord is really the only way to deal with the connection.

I was surprised at how good the OPPO sounded when used as a source to feed the Pass Labs setup. It’s amazing that such small sources can reproduce sound so well, compared to just a few years ago.

The OPPO DAC and Headphone Amplifier On the Bench

I ran the two most important tests, 1 kHz THD+N and IMD, instead of the full battery of tests. I used 16/44.1 and 24/192 PCM. I did not use any DSD test signals. I took the signal from the headphone output, and loaded it with two 39 ohm resistors. I used the high gain setting but no bass boost. The volume control was set to its maximum.

At 1 kHz, and 16/44.1, output was nearly 1 volt, and distortion was 0.016%.

IMD was 0.008%. Impressive. This is why there was improved detail.

Going to 24/192, distortion was the same as 16/44.1 with the 1 kHz test tone.

IMD was a bit lower using 24/192. Ther are some noticeable peaks at 41 kHz and 49 kHz. However, they are far out of the audible band.

Conclusions about the OPPO HA-2 DAC and Headphone Amplifier

OPPO continues to introduct products that have very high quality parts and performance, but are very affordable. The HA-2 is a very useful addition to your smart phone, and is an inexpensive, tempting accessory. I recommend that you yield to your temptation.

John E. Johnson, Jr. holds four university degrees, and has published numerous scientific books (three in 2014 and one in 2015), along with dozens of scientific articles on biomedical research topics as well as imaging technology. He was Editor-in-Chief of two medical/scientific journals for 20 years. John holds several patents, including one on high resolution image analysis and one on a surgical instrument. Dr. Johnson has been affiliated with NASA, The National Institutes of Health, The Johns Hopkins University, Stanford Research Institute, and The University of California at Berkeley. He is currently the Editor-in-Chief of Secrets of Home Theater and High Fidelity. John has been involved in audio and video for more than 50 years, having built radio transmitters, amplifiers, turntables, and speakers from scratch. He is President of the consulting firm Scientific Design and Information, Inc., which is based in Redwood City, California. He is also the founder of the Northern California Audio Video Association, which is now called The Bay Area Audio Society. Here is a list of the Editor's equipment that he uses in product reviews.

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